This invention relates to semiconductor quantum well devices and more particularly to devices of this type which can change their optical characteristics.
It is well known in the prior art that semiconductor quantum well devices can be caused to present changes in their optical characteristics. See, for example, U.S. Pat. No. 4,525,687 issued to D. S. Chemla et al. on June 25, 1985. In this Chemla et al. patent a semiconductor device is described having multiple quantum well structures and this device can change its optical characteristics by applying different potentials across the multiple quantum well layers. As shown in FIG. 25 of that patent, an array of such devices can be placed on a substrate and the individual devices can be field controlled by electric potentials in order to change the absorption presented by each of the devices in the array.
With integrated circuits becoming larger and larger, the possibility of optically reading the information developed on such circuits will become more desirable. Devices of the type described in the above-identified Chemla et al. patent can be placed at appropriate points of a very large scale integrated circuit in order to provide a means of optically reading the information that is developed in the circuit. The devices in the above-identified Chemla et al. patent do require a precise stable operating wavelength from the optical source used to read such devices. Less difficulty would be presented in the design of the integrated circuit if the quantum well layers could provide a change in their optical characteristics in accordance with the information presented by the electrical devices without stringent tolerance on the required operating wavelength.